PROJECT SUMMARY Portrayals of vaping in televised e-cigarettes ads, which are currently unregulated and broadcast widely, could adversely impact young adult smokers? use of conventional cigarettes by triggering urges to smoke, and more intensive smoking behaviors. There is little known about the causal links between exposure to vaping images in e-cigarette ads, urge to smoke a conventional cigarette, and objective measures of conventional cigarette smoking intensity. This lack of knowledge impedes efforts to protect young adults, who have the highest prevalence of dual-use of cigarettes and e-cigarettes (current smokers who also use e-cigarettes) and are the primary target of e-cigarette advertising. Our long-term goal is to generate more effective strategies to reduce smoking among young adults who have the highest prevalence of smoking. The objective of this study, which is the next step toward this goal, is to identify key factors within tobacco advertising that influence young adult smoking in order to inform targeted interventions. Our central hypothesis is that vaping portrayals have similar effects as smoking cues on urge to smoke and can promote more intensive smoking among young adult smokers. Our rationale for this hypothesis is based on cue reactivity research and theory. To test this hypothesis, we will conduct a randomized controlled experiment among young adult dual-users (current smokers who also vape) aged 21-30 years. Participants will be randomly assigned to one of 3 video conditions to view: 1) e-cigarette ads containing vaping portrayals, 2) control e-cigarette ads edited to remove vaping portrayals, or 3) control neutral videos. Our specific aims are to demonstrate the causal link between vaping portrayals in e-cigarette ads and subjective measures of urge to smoke among dual-users (QSU-brief) (Aim 1) and demonstrate the causal link between vaping portrayals in e-cigarette ads and objective measures of smoking intensity based on puffing topography measures (Aim 2). The proposed research is innovative because it will be the first to apply a randomized controlled experiment to directly observe smoking behavior within the e-cigarette cue reactivity research paradigm, itself a newly emerging area of inquiry. This research is significant because it will provide the first causal evidence to examine whether specific content within e- cigarette ads directly increases smoking behavior among young adults, which addresses a priority research interest of the NIH-FDA Tobacco Regulatory Science Program (the impact of tobacco marketing). Impact: The successful completion of this study will provide evidence to determine whether vaping portrayals in e-cigarette ads promote smoking among young adults. This evidence will support the development and implementation of policy interventions, including advertising restrictions, as well as anti-smoking health communication campaigns that would mitigate harm to public health from e-cigarette ads.